Named vector multi search

[dirkkul]

What's being changed:

Superseeds #4955
First part of #5138

Adds multi target support to all vector searchs (nearXXX + hybrid).

This flow is the following:

• Users can provide multiple target vectors
• Each target vector is searched concurrently.
• The results of different target vectors will contain different objects, which makes it hard to combine things
  • Missing distances will be computed. This requires a new remote endpoint as some objects have to be fetched from other nodes. This happens concurrently.
• Combinations happens when all distances are ready

To run the python integration tests use ./test/run.sh --acceptance-only-python or install the latest client using pip install git+https://github.com/weaviate/weaviate-python-client.git@named_vector_multi_search

GQL support for different combination methods is still missing - I will add that later in a separate PR

Review checklist

• Documentation has been updated, if necessary. Link to changed documentation:
• Chaos pipeline run or not necessary. Link to pipeline:
• All new code is covered by tests where it is reasonable.
• Performance tests have been run or not necessary

[sonarcloud]

Quality Gate passed

Issues
21 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
2.5% Duplication on New Code

See analysis details on SonarCloud